1. Field of the Invention
The present invention relates to a process for preparing a combined wiring substrate. More particularly it relates to a process for preparing a large-sized combined wiring substrate by mechanically joining a plurality of substrates each having a pattern of wiring and by electrically connecting the patterns of wiring. The process is suitable for preparing a large-sized liquid crystal display by connecting mutually a plurality of independently prepared liquid crystal display substrates.
2. Discussion of Background
Much investment such as a manufacturing apparatus is required to produce a large-sized wiring substrate used for, for instance, a liquid crystal display device. Further, there are many problems that when a wiring substrate having a large surface area is to be prepared, possibilities of breaking of wire and short circuit due to deposition of dust during manufacturing steps increase; the electric characteristics become ununiform due to uneven quality of a film on the surface of the substrate, and it is difficult to transport or handle the substrate. Accordingly, it has been studied to combine a plurality of separately prepared wiring substrates to form a large-sized liquid crystal display.
In the following, an example of preparing a combined liquid crystal display will be described.
FIG. 8 is a cross-sectional view showing a conventional combined liquid crystal display disclosed, for instance, in Japanese Unexamined Patent Publication No. 124527/1987. In FIG. 8, a reference numeral 1 designates a circuit substrate for a liquid crystal display, a numeral 2 designates liquid crystal, a numeral designates an opposing substrate which opposes with a suitable space to the circuit substrate 1, a numeral 4 3 designates an adhesive agent to seal the space between the circuit substrate 1 and the opposing substrate 3, a numeral 5 designates a spacer to maintain the circuit substrate 1 and the opposing substrate 3 at a suitable gap, a numeral 6 designates a thin plate which sealingly closes an end plane of the liquid crystal display and a numeral 7 designates an adhesive agent to bond opposing liquid crystal display blocks each of which is constituted by the above-mentioned materials. A combined liquid crystal display which function as a large-sized single liquid crystal display is formed by arranging a number of the liquid crystal display blocks and by bonding the mutually opposing end surfaces of the blocks with an adhesive agent 7.
In the conventional combined liquid crystal display prepared by the above-mentioned process, there was a problem that a person who watch the display had a strange feeling because there were non-display regions between adjacent liquid crystal display blocks, which correspond to an area formed by several tends or more picture elements. Further, in the conventional process, the adjacent liquid crystal display blocks adjacent each other were not electrically connected. Accordingly, it was necessary to mount a circuit on each of the display blocks to drive them. It was not easy to mount the circuits.